Beam power with multipoint broadcast

ABSTRACT

A beam power source transmits a signal indicating power availability, receives a request for power in response, and beams power in response to the request.

CROSS-REFERENCE TO RELATED APPLICATIONS Related Applications

The present application is related to U.S. patent application Ser. No.To be Assigned, titled BEAM POWER FOR LOCAL RECEIVERS, naming RoderickA. Hyde, Muriel Y. Ishikawa, Jordin T. Kare, Thomas J. Nugent, Jr.,Thomas A. Weaver, Lowell L. Wood, Jr., and Victoria Y. H. Wood asinventors, filed 30 Sep. 2008, which is currently co-pending [AttorneyDocket No. 0206-009-003-000000].

The present application is related to U.S. patent application Ser. No.To be Assigned, titled BEAM POWER WITH MULTIPOINT RECEPTION, namingRoderick A. Hyde, Muriel Y. Ishikawa, Jordin T. Kare, Thomas J. Nugent,Jr., Thomas A. Weaver, Lowell L. Wood, Jr., and Victoria Y. H. Wood asinventors, filed 30 Sep. 2008, which is currently co-pending [AttorneyDocket No. 0206-009-005-000000].

The present application is related to U.S. patent application Ser. No.To be Assigned, titled BEAM POWER WITH BROADCASTER IMPINGEMENTDETECTION, naming Roderick A. Hyde, Muriel Y. Ishikawa, Jordin T. Kare,Thomas J. Nugent, Jr., Thomas A. Weaver, Lowell L. Wood, Jr., andVictoria Y. H. Wood as inventors, filed 30 Sep. 2008, which is currentlyco-pending [Attorney Docket No. 0206-009-006-000000].

The present application is related to U.S. patent application Ser. No.To be Assigned, titled BEAM POWER WITH RECEIVER IMPINGEMENT DETECTION,naming Roderick A. Hyde, Muriel Y. Ishikawa, Jordin T. Kare, Thomas J.Nugent, Jr., Thomas A. Weaver, Lowell L. Wood, Jr., and Victoria Y. H.Wood as inventors, filed 30 Sep. 2008, which is currently co-pending[Attorney Docket No. 0206-009-007-000000].

The present application is related to U.S. patent application Ser. No.To be Assigned, titled BEAM POWER WITH BEAM REDIRECTION, naming RoderickA. Hyde, Muriel Y. Ishikawa, Jordin T. Kare, Thomas J. Nugent, Jr.,Thomas A. Weaver, Lowell L. Wood, Jr., and Victoria Y. H. Wood asinventors, filed 30 Sep. 2008, which is currently co-pending [AttorneyDocket No. 0206-009-008-000000].

The present application is related to U.S. patent application Ser. No.To be Assigned, titled BEAM POWER WITH MULTIPLE POWER ZONES, namingRoderick A. Hyde, Muriel Y. Ishikawa, Jordin T. Kare, Thomas J. Nugent,Jr., Thomas A. Weaver, Lowell L. Wood, Jr., and Victoria Y. H. Wood asinventors, filed 30 Sep. 2008, which is currently co-pending [AttorneyDocket No. 0206-009-009-000000].

SUMMARY

In one aspect, a power source configured to beam power to a receivingunit includes a location unit and a power beaming unit. The locationunit is configured to locate a receiving unit in need of power byinitiating contact with the receiving unit by broadcasting a signalindicative of its ability to supply power and by receiving a request forpower from the receiving unit in response to the broadcast signal. Thepower beaming unit is configured to beam power to the receiving unit.Broadcasting may include initiating broadcasting according to a timeschedule, or in response to a detected condition (e.g., detection of aperson in the broadcast area). The power beaming unit may be configuredto beam power within an enclosed space. The location unit may beconfigured to receive a request for power in the form of a transmissionfrom the receiving unit or of a reflection of the broadcast signal fromthe receiving unit (e.g., a modulated reflection, which the powerbeaming unit may be configured to interpret). The request for power fromthe receiving unit may include location information for the receivingunit, for example encoded in a signal received from the receiving unit,determinable from a path of the received signal (e.g., by scanning, byimaging, or by directional antenna), or based on identifying informationincluded in the received signal (e.g., by determining a previouslocation or by accessing a location database). The location unit may beconfigured to determine an attitude of the receiving unit. The locationunit may be configured to broadcast or to receive an electromagneticsignal (e.g., optical or RF) or an acoustic signal. The location unitmay be configured to receive a request for power including informationdescribing power needs (e.g., power type, wavelength, pulsecharacteristics, power amount, energy amount, polarization,power-vs-time profile, time window, offset of aperture, aperture size orattitude, acceptable price, ability to pay, mode of payment, oridentifying information for the receiving unit, in which case thelocation unit may be configured to determine additional informationabout power needs of the receiving unit on the basis of the identifyinginformation). The power source may further include a decision unitconfigured to determine whether to beam power from the power beamingunit, which may further be configured to determine whether to initiate,suspend, or terminate power beaming. The decision unit may be configuredto receive a signal confirming receipt or amount of power received, andmay be configured to compare the amount of power received with theamount transmitted. The decision unit may be configured to accept powerrequest information from the power receiving unit (e.g., requested powercharacteristic(s) or proposed payment terms) to determine whether tobeam power from the power beaming unit. The location unit may beconfigured to transmit data to the receiving unit, for example bymodulating the beamed power from the power beaming unit or via aseparate channel. The transmitted data may include, for example,information for negotiating power delivery characteristic(s) or paymentcharacteristic(s), identity authentication information for the receivingunit, or power receipt monitoring data. The power beaming unit may beconfigured to beam power directly to the receiving unit, or via abeam-directing element, and may be configured to gradually increase anamount of power beamed from the power beaming unit. The power beamingunit may be configured to beam electromagnetic power (e.g., optical orRF), and may include a laser. The power beam may be pulsed orcontinuous. The power source may further include an impingement detectorconfigured to detect that the beamed power has encountered anobstruction, for example by detecting scattered or reflected radiation.The power beaming unit may be configured to suspend or terminatetransmission upon detection that the beamed power has encountered anobstruction.

In another aspect, a power source configured to beam power to areceiving unit includes a location unit and a power beaming unit. Thelocation unit is configured to locate a receiving unit in need of powerby scanning a signal indicative of its ability to supply power andreceiving a request for power from the receiving unit in response to thescanned signal. The request for power is in the form of a reflection ofthe scanned signal, which may optionally be modulated. The power beamingunit is configured to beam power to the receiving unit. The locationunit may be configured to discontinue scanning upon receiving therequest for power. The power beaming unit may be configured to beampower within an enclosed space. Scanning may include initiating scanningaccording to a time schedule or in response to a detected condition(e.g., detection of a person in a broadcast area). The location unit maybe configured to receive a request for power in the form of a modulatedreflection of the scanned signal from the receiving unit, and may befurther configured to interpret the modulated reflection. The locationunit may be configured to receive a request for power in the form of areflection of the scanned signal and a further transmission from thereceiving unit (e.g., an electromagnetic or acoustic transmission, or atransmission over a wired connection or over the internet). The requestfor power from the receiving unit may include location information forthe receiving unit, for example encoded in a signal received from thereceiving unit or determinable from a path of a signal received from thereceiving unit. The location information for the receiving unit mayinclude identifying information for the receiving unit, in which casethe location unit may be configured to determine a location for thereceiving unit on the basis of the identifying information. The locationunit may be configured to determine a location for the receiving unit bydetermining a previous location for the unit or by accessing a locationdatabase. The location unit may be configured to determine an attitudeof the receiving unit, and may broadcast an electromagnetic signal(e.g., optical or RF) or an acoustic signal. The location unit mayconfigured to receive a request for power including informationdescribing power needs (e.g., power type, wavelength, pulsecharacteristics, power amount, energy amount, polarization,power-vs-time profile, time window, offset of aperture, aperture size,aperture attitude, acceptable price, ability to pay, mode of payment, oridentifying information for the receiving unit, in which case thelocation unit may be configured to determine additional informationabout power needs of the receiving unit on the basis of the identifyinginformation). The power source may further comprise a decision unitconfigured to determine whether to beam power from the power beamingunit. The decision unit may be configured to accept power requestinformation (e.g., a requested characteristic or proposed payment terms)from the power receiving unit to determine whether to beam power fromthe power beaming unit, and may be configured to determine whether toinitiate, suspend, or terminate power beaming. The decision unit may beconfigured to receive a signal confirming receipt of received power oran amount of power received, and may further be configured to comparethe amount of power received with an amount of power transmitted. Thelocation unit may be configured to transmit data to the receiving unit,for example by modulating the beamed power from the power beaming unitor via a separate channel from the beamed power from the power beamingunit (e.g., for negotiating a power delivery characteristic or a paymentcharacteristic, for authenticating identity of the receiving unit, orfor monitoring receipt of power by the receiving unit). The powerbeaming unit may be configured to beam power directly to the receivingunit, or to a beam-directing element configured to redirect the power tothe receiving unit, and may be configured to gradually increase anamount of power beamed from the power beaming unit. The power beamingunit may be configured to beam electromagnetic power (e.g., optical orRF), and may include a laser that generates a power beam. The power beammay be pulsed or continuous. The power source may further include animpingement detector configured to detect that the beamed power hasencountered an obstruction, for example by detecting scattered orreflected radiation. The power beaming unit may be configured to suspendor terminate transmission upon detection that the beamed power hasencountered an obstruction.

In another aspect, a power receiver configured to receive power beamedfrom a power source includes a signal receiver configured to detect abroadcast signal indicative of power availability, a transmission unitconfigured to transmit a request for power in response to the detectedsignal, and a power receiving unit configured to accept power beamedfrom a power source at an aperture. The power receiving unit may beconfigured to accept electromagnetic (e.g., optical or RF) or acousticpower. The transmission unit may be configured to transmit a request forpower by generating and transmitting a request signal or by reflecting(and optionally modulating) the broadcast signal. The request for powermay include a signal including location information for the powerreceiving unit, or power or economic needs of the power receiver (e.g.,power type, wavelength, pulse characteristics, power amount, energyamount, polarization, power-vs-time profile, time window, offset ofaperture, aperture size, aperture attitude, acceptable price, ability topay, mode of payment, or identifying information for the receivingunit). The signal receiver may configured to receive an electromagneticsignal (e.g., optical or RF) or an acoustic signal. The power receivermay be configured to receive a data transmission from a power source,for example for negotiating power delivery or payment characteristics,for negotiating termination of power delivery, for authenticatingidentity of the power receiver, or for monitoring receipt of power bythe power receiver. The power beam from the power source may serve as acarrier wave for the data transmission, or the data transmission may beseparate from the power beam. The power receiving unit may be configuredto reposition itself to adjust power reception, to communicate a powerreception level to a user, to communicate a power reception level to thepower source, or to recommend to a user a change in orientation orposition to adjust power reception.

In another aspect, a power receiver configured to receive power beamedfrom a power source includes a signal receiver configured to detect ascanned signal indicative of power availability, a transmission unitconfigured to transmit a request for power in the form of aretroreflection of the detected signal, and a power receiving unitconfigured to accept power beamed from a power source. The transmissionunit may be further configured to modulate the retroreflected broadcastsignal or to transmit an additional power request signal to the powersource in response to the scanned signal (e.g., an electromagnetic or anacoustic signal, a signal over a wired channel, or a signal via theinternet). The transmission unit may be configured to transmit a requestfor power including a signal including location information for thepower receiving unit, information describing power needs of the powerreceiver (e.g., power type, wavelength, pulse characteristics, poweramount, energy amount, polarization, power-vs-time profile, time window,offset of aperture, aperture size, or aperture attitude), or informationdescribing economic parameters of power transmission (e.g., acceptableprice, ability to pay, mode of payment, or identifying information forthe receiving unit). The signal receiver may be configured to receive anelectromagnetic (e.g., optical or RF) or acoustic signal. The powerreceiver may be configured to receive a data transmission from a powersource, for example for negotiating power delivery characteristics, fornegotiating payment characteristics, for negotiating termination ofpower delivery, for authenticating identity of the power receiver, orfor monitoring receipt of power by the power receiver. The power beammay serve as a carrier wave for the data transmission, or the datatransmission may be separate from the power beam. The power receivingunit may be configured to reposition itself to adjust power reception,to communicate a power reception level to a user, to communicate a powerreception level to the power source, or to recommend to a user a changein orientation or position to adjust power reception. In another aspect,a method of transmitting power includes initiating contact with areceiving unit by broadcasting a signal (e.g., electromagnetic oracoustic) indicating an ability to supply power, receiving a request forpower from the receiving unit in response to the broadcast signal, andbeaming power (e.g., electromagnetic power such as optical or RF, oracoustic power) to the receiving unit in response to the request.Beaming power may include beaming power within an enclosed space.Broadcasting may be according to a time schedule or in response to adetected condition (e.g., detection of a person in a broadcast area).Receiving a request for power may include receiving a transmission fromthe receiving unit or receiving a reflection of the broadcast signalfrom the receiving unit, and may include receiving location informationfor the receiving unit (e.g., encoded into a signal received from thereceiving unit or determined by a path of a received signal, for exampledetermined by scanning, imaging, or using a directional antenna). Therequest for power may include information describing power needs (e.g.,power type, wavelength, pulse characteristics, power amount, energyamount, polarization, power-vs-time profile, time window, offset ofaperture, aperture size, aperture attitude, acceptable price, ability topay, mode of payment, or identifying information for the receivingunit). Receiving the request for power may include receiving identifyinginformation for the receiving unit and determining a location for thereceiving unit using the identifying information (e.g., by determining aprevious location for the receiving unit or by accessing a locationdatabase). The method may include determining an attitude of thereceiving unit. The method may further include sending a signal to thereceiving unit (e.g., electromagnetic or acoustic), for example bymodulating the beamed power to the receiving unit or by transmitting asignal via a separate channel from the beamed power. Power may be beameddirectly to the receiving unit or to a beam-directing element configuredto redirect the power to the receiving unit, and may include graduallyincreasing an amount of power beamed.

In another aspect, a method of transmitting power includes initiatingcontact with a receiving unit by scanning a signal indicating an abilityto supply power (e.g., an electromagnetic or acoustic signal), receivinga request for power from the receiving unit in response to the scannedsignal in the form of a reflection of the signal, and beaming power(e.g., electromagnetic power such as optical or RF) to the receivingunit in response to the request. The method may further includediscontinuing scanning the signal in response to receiving a request forpower. Beaming power may include beaming power within an enclosed space.Scanning may include initiating scanning according to a time schedule orin response to a detected condition such as detection of a person in asignaling area. Receiving a request for power from the receiving unitincludes receiving the request in the form of a modulated reflection ofthe scanned signal, and the method may further include interpreting themodulated reflection. The method may further include receivingadditional power request information from the power receiver via adifferent channel from the request for power, for example anelectromagnetic or acoustic transmission, a wired transmission, or aninternet transmission. Receiving a request for power from the receivingunit may include receiving the request in the form of a retroreflectionof the scanned signal, and may include receiving location informationfor the receiving unit, for example encoded into a signal received fromthe receiving unit or determined from a path of a signal received fromthe receiving unit. Receiving the request for power may includereceiving information describing power needs (e.g., power type,wavelength, pulse characteristics, power amount, energy amount,polarization, power-vs-time profile, time window, offset of aperture,aperture size, aperture attitude, acceptable price, ability to pay, modeof payment, or identifying information for the receiving unit).Receiving the request for power may include receiving identifyinginformation for the receiving unit, and determining a location for thereceiving unit using the identifying information, for example bydetermining a previous location for the receiving unit or by accessing alocation database. The method may include determining an attitude of thereceiving unit, and may further include sending a signal to thereceiving unit (e.g., an electromagnetic signal such as an optical or RFsignal or an acoustic signal), for example by modulating the beamedpower to the receiving unit or by transmitting a signal via a separatechannel from the beamed power. Power may be beamed directly to thereceiving unit or to a beam-directing element configured to redirect thepower to the receiving unit, and beaming may include graduallyincreasing an amount of power beamed. In another aspect, a method oftransmitting power includes broadcasting a signal indicating an abilityto supply power, receiving a request for power from a receiving unit inresponse to the broadcast signal, and determining whether to beam powerto the receiving unit in response to the request. The method may furtherinclude beaming power to the receiving unit or receiving power requestinformation from the receiving unit (e.g., a requested characteristic ofbeamed power or proposed payment terms, in which case the method mayfurther include sending counteroffer payment terms) and using thereceived information to determine whether to beam power to the receivingunit. Determining whether to beam power to the receiving unit mayinclude determining whether to initiate, suspend, or terminate powerbeaming. In another aspect, a method of transmitting power includesscanning a signal indicating an ability to supply power, receiving arequest for power from a receiving unit in response to the scannedsignal, and determining whether to beam power to the receiving unit inresponse to the request. The method may further include beaming power tothe receiving unit or receiving power request information from thereceiving unit (e.g., a requested characteristic of beamed power orproposed payment terms, in which case the method may further includesending counteroffer payment terms) and using the received informationto determine whether to beam power to the receiving unit. Determiningwhether to beam power to the receiving unit may include determiningwhether to initiate, suspend, or terminate power beaming.

In another aspect, a method of receiving power includes receiving aninitial broadcast signal (e.g., an electromagnetic or acoustic signal)indicating an ability of a power source to supply power, transmitting arequest for power in response to the broadcast signal, and receivingbeamed power in response to the request. Transmitting a request forpower may include generating and transmitting a request signal orreflecting the broadcast signal (e.g., retroreflecting or modulating thebroadcast signal). Transmitting a request for power may includetransmitting location information for a power receiver or informationdescribing power needs of a power receiver (e.g., power type,wavelength, pulse characteristics, power amount, energy amount,polarization, power-vs-time profile, time window, offset of aperture,aperture size, aperture attitude, acceptable price, ability to pay, modeof payment, or identifying information for the receiving unit). Themethod may further include receiving a data transmission from the powersource, for example superimposed on a power beam or in a separatechannel from the beamed power. Receiving beamed power may includerepositioning a power receiving unit to adjust power reception,communicating a power reception level to a user, communicating a powerreception level to the power source, recommending to a user a change inorientation or position to adjust power reception, or changingorientation or position for the power receiving unit to adjust powerreception. Transmitting a request for power may include transmittingidentity information. The method may further include receiving a datatransmission from the power source for negotiating a power deliverycharacteristic, for negotiating a payment characteristic, fornegotiating termination of power delivery, for authenticating identity,or for monitoring receipt of power.

In another aspect, a method of receiving power includes receiving aninitial signal indicating an ability of a power source to supply power(e.g., an electromagnetic or acoustic signal), transmitting a requestfor power in response to the broadcast initial signal in the form of anoptionally modulated retroreflection of the initial signal, andreceiving beamed power in response to the request. Transmitting arequest for power may include transmitting location information for apower receiver, or transmitting information describing power needs of apower receiver (e.g., power type, wavelength, pulse characteristics,power amount, energy amount, polarization, power-vs-time profile, timewindow, offset of aperture, aperture size, aperture attitude, acceptableprice, ability to pay, mode of payment, or identifying information forthe receiving unit). The method may further include receiving a datatransmission from the power source, for example superimposed on a powerbeam or in a separate channel from the beamed power. Receiving beamedpower may include repositioning a power receiving unit to adjust powerreception, communicating a power reception level to a user,communicating a power reception level to the power source, recommendingto a user a change in orientation or position to adjust power reception,or changing orientation or position for the power receiving unit toadjust power reception. Transmitting a request for power may includetransmitting identity information. The method may further includereceiving a data transmission from the power source for negotiating apower delivery characteristic, for negotiating a payment characteristic,for negotiating termination of power delivery, for authenticatingidentity, or for monitoring receipt of power. In another aspect, a powersource configured to beam power to a receiving unit includes a locationunit configured to locate a receiving unit in need of power and a powerbeaming unit configured to beam power to the receiving unit. Thelocation unit locates the receiving unit by receiving an optical signalrequesting power from the receiving unit in response to the broadcastsignal and transmitting a response to the optical signal indicating awillingness to transmit power. Receiving an optical signal may includedetecting power receiver optical indicia, receiving an optical beam, orreceiving a laser beam. In another aspect, a power source configured tobeam power to a receiving unit includes a power beaming unit configuredto beam optical power and a location unit configured to locate areceiving unit in need of power by receiving a radio frequency signalrequesting power from the receiving unit, locating an optical beam pathfrom the power beaming unit to the receiving unit, and transmitting aresponse to the optical signal indicating a willingness to transmitpower. In another aspect, a power source configured to beam power to areceiving unit includes a location unit and a power beaming unitconfigured to beam power to the receiving unit. The location unit isconfigured to locate a receiving unit in need of power by receiving aninternet communication requesting power from the receiving unit andtransmitting a response to the optical signal indicating a willingnessto transmit power. In another aspect, a system for supplying beamedpower to a receiving unit includes a location unit and a plurality ofpower beaming units, each configured to beam power to a receiving unit.The location unit is configured to locate a target receiving unit inneed of power by broadcasting a signal indicative of the system'sability to supply power (e.g., an electromagnetic or acoustic signal)and receiving a request for power from the receiving unit in response tothe broadcast signal. The location unit may be colocated with one of theplurality of power beaming units. The system may include a plurality oflocation units, in which case each power beaming unit may be colocatedwith a member of the plurality of location units. The system may furtherinclude a decision unit configured to designate a member of theplurality of power beaming units to beam power to a receiving unit inresponse to a request therefrom, for example the member of the pluralityof power beaming units in closest physical proximity to the requestingreceiving unit, the member of the plurality of power beaming unitshaving the shortest unobstructed power beam path length, the member ofthe plurality of power beaming units having the highest projected powerintensity, or a member of the plurality of power beaming units having apower characteristic (e.g., power type, wavelength, pulsecharacteristics, power amount, polarization, power-vs-time profile, ortime window) or transaction characteristic (e.g., acceptable price,ability to pay, mode of payment, or identifying information for thereceiving unit) corresponding to a characteristic requested by thereceiving unit. The decision unit may be configured to determine whetherto initiate, suspend, or terminate power beaming. The location unit maybe configured to receive a request for power in the form of atransmission from the receiving unit or in the form of a reflection ofthe broadcast signal from the receiving unit. The request for power fromthe receiving unit may include location information for the receivingunit, for example encoded in a signal received from the receiving unitor determined from a path of a signal received from the receiving unit(e.g., by scanning, by imaging, or by using a directional antenna). Thelocation unit may be configured to receive a request for power includinginformation describing power needs (e.g., power type, wavelength, pulsecharacteristics, power amount, energy amount, polarization,power-vs-time profile, time window, offset of aperture, aperture size,aperture attitude, acceptable price, ability to pay, mode of payment, oridentifying information for the receiving unit). The location unit maybe configured to exchange data with the receiving unit, and may beconfigured to transmit data to the receiving unit by modulating thebeamed power from a member of the plurality of power beaming units orvia a separate channel from the beamed power from a member of theplurality of power beaming units. At least a subset of the plurality ofpower beaming units may be configured to beam power directly to thereceiving unit or to a beam-directing element configured to redirect thepower to the receiving unit, and may be configured to gradually increasean amount of power beamed from the power beaming unit. At least a subsetof the plurality of power beaming units may be configured to beamelectromagnetic power (e.g. optical or RF power),In another aspect, asystem for supplying beamed power to a receiving unit includes alocation unit and a plurality of power beaming units, each configured tobeam power to a receiving unit. The location unit is configured tolocate a target receiving unit in need of power by scanning a signalindicative of the system's ability to supply power and receiving arequest for power from the receiving unit in response to the scannedsignal. The location unit may be colocated with one of the plurality ofpower beaming units. The system may include a plurality of locationunits, in which case each power beaming unit may be colocated with amember of the plurality of location units. The system may furtherinclude a decision unit configured to designate a member of theplurality of power beaming units to beam power to a receiving unit inresponse to a request therefrom, for example the member of the pluralityof power beaming units in closest physical proximity to the requestingreceiving unit, the member of the plurality of power beaming unitshaving the shortest unobstructed power beam path length, the member ofthe plurality of power beaming units having the highest projected powerintensity, or a member of the plurality of power beaming units having apower characteristic (e.g., power type, wavelength, pulsecharacteristics, power amount, polarization, power-vs-time profile, ortime window) or transaction characteristic (e.g., acceptable price,ability to pay, mode of payment, or identifying information for thereceiving unit) corresponding to a characteristic requested by thereceiving unit. The decision unit may be configured to determine whetherto initiate, suspend, or terminate power beaming. The location unit maybe configured to receive a request for power in the form of atransmission from the receiving unit or in the form of a reflection ofthe scanned signal from the receiving unit. The request for power fromthe receiving unit may include location information for the receivingunit, for example encoded in a signal received from the receiving unit,determined from a path of a signal received from the receiving unit(e.g., by scanning, by imaging, or by using a directional antenna), ordetermined from a position of a component of the location unit at thetime of receipt of the request for power (e.g., the direction of thescanning beam at the time of the request). The location unit may beconfigured to receive a request for power including informationdescribing power needs (e.g., power type, wavelength, pulsecharacteristics, power amount, energy amount, polarization,power-vs-time profile, time window, offset of aperture, aperture size,aperture attitude, acceptable price, ability to pay, mode of payment, oridentifying information for the receiving unit). The location unit maybe configured to exchange data with the receiving unit, and may beconfigured to transmit data to the receiving unit by modulating thebeamed power from a member of the plurality of power beaming units orvia a separate channel from the beamed power from a member of theplurality of power beaming units. At least a subset of the plurality ofpower beaming units may be configured to beam power directly to thereceiving unit or to a beam-directing element configured to redirect thepower to the receiving unit, and may be configured to gradually increasean amount of power beamed from the power beaming unit. At least a subsetof the plurality of power beaming units may be configured to beamelectromagnetic power (e.g. optical or RF power). The location unit maybe configured to initiate broadcasting a signal in response to areceived initiation signal, for example broadcast by the receiving unit,requested by the receiving unit, or received from a triggering unitremote from the receiving unit.

In another aspect, a method of supplying beamed power from a pluralityof power beaming units to a receiving unit includes broadcasting asignal indicating an ability to supply power (e.g., an electromagneticor acoustic signal), receiving a request for power from the receivingunit in response to the broadcast signal, and beaming power (e.g.,electromagnetic power such as optical or RF power) from one of theplurality of power beaming units to the receiving unit in response tothe request. Broadcasting a signal and receiving a request for power mayoccur at a common location, and broadcasting a signal may includebroadcasting a signal from a plurality of locations. Broadcasting mayoccur according to a time schedule or in response to a detectedcondition. Receiving a request may include receiving a request from aplurality of locations. Beaming power may include beaming power withinan enclosed space. Receiving a request for power may include receiving atransmission from the receiving unit or receiving a reflection of thebroadcast signal from the receiving unit, and may include receivinglocation information for the receiving unit, for example determined froma path of a signal received from the receiving unit (e.g., by scanning,imaging, or using a directional antenna), information describing powerneeds (e.g., power type, wavelength, pulse characteristics, poweramount, energy amount, polarization, power-vs-time profile, time window,offset of aperture, aperture size, aperture attitude, acceptable price,ability to pay, mode of payment, or identifying information for thereceiving unit), or identifying information for the receiving unit, inwhich case a location for the receiving unit may be determined, forexample by determining a previous location for the receiving unit oraccessing a location database. The method may further includedetermining an attitude of the receiving unit, or sending a signal tothe receiving unit (e.g., an electromagnetic or acoustic signal), forexample by modulating the beamed power to the receiving unit or via aseparate channel from the beamed power. Beaming power may includebeaming power directly to the receiving unit or to a beam-directingelement configured to redirect the power to the receiving unit, and mayinclude gradually increasing an amount of power beamed.

In another aspect, a method of supplying beamed power from a pluralityof power beaming units to a receiving unit includes scanning a signalindicating an ability to supply power (e.g., an electromagnetic oracoustic signal), receiving a request for power from the receiving unitin response to the scanned signal in the form of a reflection of thescanned signal, and beaming power (e.g., electromagnetic power such asoptical or RF) from one of the plurality of power beaming units to thereceiving unit in response to the request. Scanning a signal andreceiving a request for power may occur at a common location, andscanning a signal may include scanning a signal from a plurality oflocations. Scanning may occur according to a time schedule or inresponse to a detected condition. Receiving a request may includereceiving a request from a plurality of locations. Beaming power mayinclude beaming power within an enclosed space. Receiving a request forpower may include receiving a transmission from the receiving unit orreceiving a reflection of the broadcast signal from the receiving unit,and may include receiving location information for the receiving unit,for example determined from a path of a signal received from thereceiving unit (e.g., by scanning, imaging, or using a directionalantenna), information describing power needs (e.g., power type,wavelength, pulse characteristics, power amount, energy amount,polarization, power-vs-time profile, time window, offset of aperture,aperture size, aperture attitude, acceptable price, ability to pay, modeof payment, or identifying information for the receiving unit), oridentifying information for the receiving unit, in which case a locationfor the receiving unit may be determined, for example by determining aprevious location for the receiving unit or accessing a locationdatabase. The method may further include determining an attitude of thereceiving unit, or sending a signal to the receiving unit (e.g., anelectromagnetic or acoustic signal), for example by modulating thebeamed power to the receiving unit or via a separate channel from thebeamed power. Beaming power may include beaming power directly to thereceiving unit or to a beam-directing element configured to redirect thepower to the receiving unit, and may include gradually increasing anamount of power beamed.

In another aspect, a method of requesting power from one of a pluralityof power beaming units includes receiving a broadcast signal includinglocation information for a plurality of power beaming units, selecting asubset of the plurality of power beaming units for a power request, andtransmitting a request signal requesting power transmission from thesubset. Receiving a broadcast signal may include receiving a pluralityof broadcast signals, receiving a broadcast signal from each member ofthe plurality of power beaming units, receiving a single signaldescribing all members of the plurality of power beaming units, orreceiving information about power transmission characteristics of atleast one of the power beaming units. Selecting a subset may includedetermining which members of the plurality of power beaming units arecompatible with a power receiver. The method may further includereceiving a power transmission from at least one member of the subset.

In another aspect, a system for supplying beamed power to a plurality ofreceiving units includes a location unit and a power beaming unitconfigured to beam power to a plurality of receiving units in responseto the request for power. The location unit is configured to locate atarget receiving unit in need of power by broadcasting a beam indicativeof the system's ability to supply power (e.g., an electromagnetic oracoustic beam) and receiving a request for power from the receiving unitin response to the broadcast beam. The power beaming unit may beconfigured to beam power to a plurality of receiving unitssimultaneously (e.g., by splitting an output beam or by generating aplurality of output beams) or in series (e.g., by scanning a power beamto each member of the plurality of receiving units in turn or bymonitoring power needs of each member of the plurality of receivingunits and directing the power beam to each unit according to adetermination of its relative priority for power). The location unit maybe configured to receive a request for power in the form of atransmission from the receiving unit or in the form of a reflection ofthe broadcast signal from the receiving unit. The request for power fromthe receiving unit may include location information for the receivingunit (e.g., encoded in a signal received from the receiving unit ordetermined from a path of a signal received from the receiving unit, forexample by scanning or by imaging). The location unit may be configuredto receive a request for power including information describing powerneeds (e.g., power type, wavelength, pulse characteristics, poweramount, energy amount, polarization, power-vs-time profile, time window,offset of aperture, aperture size, aperture attitude, acceptable price,ability to pay, mode of payment, or identifying information for thereceiving unit), and may be configured to exchange data with thereceiving unit, for example by modulating the beamed power from thepower beaming unit or via a separate channel from the beamed power fromthe power beaming unit. The power beaming unit may be configured to beampower directly to the receiving unit or to a beam-directing elementconfigured to redirect the power to the receiving unit, and may beconfigured to gradually increase an amount of power beamed from thepower beaming unit. In another aspect, a system for supplying beamedpower to a plurality of receiving units includes a location unit and apower beaming unit configured to beam power to a plurality of receivingunits in response to the request for power. The location unit isconfigured to locate a target receiving unit in need of power byscanning a beam indicative of the system's ability to supply power(e.g., an electromagnetic or acoustic beam) and receiving a request forpower from the receiving unit in the form of a retroreflection of thescanned beam. The power beaming unit may be configured to beam power toa plurality of receiving units simultaneously (e.g., by splitting anoutput beam or by generating a plurality of output beams) or in series(e.g., by scanning a power beam to each member of the plurality ofreceiving units in turn or by monitoring power needs of each member ofthe plurality of receiving units and directing the power beam to eachunit according to a determination of its relative priority for power).The request for power from the receiving unit may include locationinformation for the receiving unit (e.g., encoded in a signal receivedfrom the receiving unit or determined from a path of a signal receivedfrom the receiving unit, for example by scanning or by imaging). Thelocation unit may be configured to receive a request for power includinginformation describing power needs (e.g., power type, wavelength, pulsecharacteristics, power amount, energy amount, polarization,power-vs-time profile, time window, offset of aperture, aperture size,aperture attitude, acceptable price, ability to pay, mode of payment, oridentifying information for the receiving unit), and may be configuredto exchange data with the receiving unit, for example by modulating thebeamed power from the power beaming unit or via a separate channel fromthe beamed power from the power beaming unit. The power beaming unit maybe configured to beam power directly to the receiving unit or to abeam-directing element configured to redirect the power to the receivingunit, and may be configured to gradually increase an amount of powerbeamed from the power beaming unit. In another aspect, a method ofsupplying beamed power to a plurality of receiving units includesbroadcasting a signal indicating an ability to supply power (e.g., anelectromagnetic or acoustic signal), receiving a request for power fromat least two members of the plurality of receiving units in response tothe broadcast signal, and beaming power to the at least two receivingunits in response to the request. Broadcasting a signal and receiving arequest for power may occur at a common location, and broadcasting asignal may include broadcasting a signal from a plurality of locations.Broadcasting may include broadcasting according to a time schedule or inresponse to a detected condition. Beaming power may include beamingwithin an enclosed space. Receiving a request for power may includereceiving a transmission from at least one member of the plurality ofreceiving units, or receiving a reflection of the broadcast signal fromat least one member of the plurality of receiving units, and may includereceiving location information for at least one member of the pluralityof receiving units, for example encoded into a signal received from theat least one member of the plurality of receiving units or determinedfrom a path of a signal received from the at least one member of theplurality of receiving units (e.g., by scanning, imaging, or using andirectional antenna). Receiving the request for power may includereceiving information describing power needs (e.g., power type,wavelength, pulse characteristics, power amount, energy amount,polarization, power-vs-time profile, time window, offset of aperture,aperture size, aperture attitude, acceptable price, ability to pay, modeof payment, or identifying information for the receiving unit) orreceiving identifying information for at least one member of theplurality of receiving units, in which case the identifying informationmay be used to determine a location for the at least one member of theplurality of receiving units, for example by determining a previouslocation for the at least one member of the plurality of receiving unitsor accessing a location database. The method may further includedetermining an attitude of at least one member of the plurality ofreceiving units, or sending a signal to at least one member of theplurality of receiving units (e.g., an electromagnetic signal or anacoustic signal), for example by modulating the beamed power to thereceiving unit or via a separate channel from the beamed power. Beamingpower may include beaming power directly to the receiving unit or to abeam-directing element configured to redirect the power to the receivingunit, and may include gradually increasing an amount of power beamed.

In another aspect, a method of supplying beamed power to a plurality ofreceiving units includes scanning a signal indicating an ability tosupply power (e.g., an electromagnetic or acoustic signal), receiving arequest for power from at least two members of the plurality ofreceiving units in the form of a reflection of the scanned signal, andbeaming power to the at least two receiving units in response to therequest. Scanning a signal and receiving a request for power may occurat a common location, and scanning a signal may include scanning asignal from a plurality of locations. Scanning may include scanningaccording to a time schedule or in response to a detected condition.Beaming power may include beaming within an enclosed space. Receiving arequest for power may include receiving location information for atleast one member of the plurality of receiving units, for exampleencoded into a signal received from the at least one member of theplurality of receiving units or determined from a path of a signalreceived from the at least one member of the plurality of receivingunits (e.g., by scanning, imaging, or using an directional antenna).Receiving the request for power may include receiving informationdescribing power needs (e.g., power type, wavelength, pulsecharacteristics, power amount, energy amount, polarization,power-vs-time profile, time window, offset of aperture, aperture size,aperture attitude, acceptable price, ability to pay, mode of payment, oridentifying information for the receiving unit) or receiving identifyinginformation for at least one member of the plurality of receiving units,in which case the identifying information may be used to determine alocation for the at least one member of the plurality of receivingunits, for example by determining a previous location for the at leastone member of the plurality of receiving units or accessing a locationdatabase. The method may further include determining an attitude of atleast one member of the plurality of receiving units, or sending asignal to at least one member of the plurality of receiving units (e.g.,an electromagnetic signal or an acoustic signal), for example bymodulating the beamed power to the receiving unit or via a separatechannel from the beamed power. Beaming power may include beaming powerdirectly to the receiving unit or to a beam-directing element configuredto redirect the power to the receiving unit, and may include graduallyincreasing an amount of power beamed.

In another aspect, a method of determining relative priority ofreceiving units for power beaming includes receiving a first request forpower from a first receiving unit including a first power specificationrequest, receiving a second request for power from a second receivingunit including a second power specification request, determining arelative priority for the first and second requests according to apredetermined selection method, and instructing a first power beamingunit to beam power to the receiving unit having a higher determinedpriority. At least one of the first and second power specificationrequests may include a datum selected from the group consisting of powertype, wavelength, pulse characteristics, power amount, polarization,power-vs-time profile, time window, acceptable price, ability to pay,mode of payment, and identifying information for the receiving unit.Determining a relative priority may include determining relativeprofitability for the first and second power specification requests ordetermining availability of power corresponding to the first and secondpower specification requests. The method may further include instructingthe first power beaming unit or the second power beaming unit to beampower to the receiving unit having a lower determined priority.Instructing the first power beaming unit to beam power may includesending a signal to the first power beaming unit or sending a signal toa remote unit configured to instruct the first power beaming unit.

In another aspect, a system for supplying beamed power includes a powerbeaming unit configured to supply power to a receiving unit in the formof a power beam, a guard beaming unit configured to produce a guard beamconfigured to substantially surround the power beam (e.g., anelectromagnetic or acoustic guard beam), and a detection unit configuredto recognize an imminent impingement on the power beam. The detectionunit includes a receiver configured to receive a guard beam reflectedfrom the receiving unit and decision circuitry configured to determinethat the reflected guard beam has been interrupted and to direct thepower beaming unit to modulate the power beam. Modulating the power beammay include suspending or terminating the power beam. The system mayfurther include a beam combiner configured to combine the power beam andthe guard beam in a substantially collinear arrangement. The guard beammay be substantially cylindrical, may include a plurality of beamsarranged around the power beam, may be configured to scan an areasubstantially surrounding the power beam, or may include a plurality ofsubstantially concentric beams. The guard beaming unit may be configuredto produce a guard beam by reflecting energy from a retroreflector arraylocated at the receiving unit, or may produce the guard beam byreflecting fringes of the power beam. The guard beam may differ inwavelength, polarity, modulation, or character from the power beam. Thedecision unit may be configured to determine a characteristic of anobject impinging on the guard beam (e.g., speed, direction, size, shape,or composition). The system may further include a beam optimization unitconfigured to use information received from the receiver to adjust apower beam characteristic (e.g., beam spot size, shape, power,intensity, or power-time profile). The power beaming unit may beconfigured to beam power within an enclosed space, and may be configuredto beam power directly to the receiving unit or to a beam-directingelement configured to redirect the power to the receiving unit. Thepower beaming unit may be configured to beam electromagnetic power(e.g., optical or RF), and may be configured to gradually increase anamount of power beamed. It may include a laser that generates a powerbeam, and may be configured to beam pulsed or continuous power. Inanother aspect, a system for supplying beamed power includes a powerbeaming unit configured to supply power to a receiving unit in the formof a power beam, a guard beaming unit configured to produce a guard beamconfigured to substantially surround the power beam (e.g., anelectromagnetic or acoustic guard beam), and a detection unit configuredto recognize an imminent impingement on the power beam. The detectionunit includes a receiver configured to receive a guard beam reflectedfrom the receiving unit and decision circuitry configured to determinethat the reflected guard beam has been interrupted and to direct thepower beaming unit to reroute the power beam. The system may furtherinclude a beam combiner configured to combine the power beam and theguard beam in a substantially collinear arrangement. The guard beam maybe substantially cylindrical, may include a plurality of beams arrangedaround the power beam, may be configured to scan an area substantiallysurrounding the power beam, or may include a plurality of substantiallyconcentric beams. The guard beaming unit may be configured to produce aguard beam by reflecting energy from a retroreflector array located atthe receiving unit, or may produce the guard beam by reflecting fringesof the power beam. The guard beam may differ in wavelength, polarity,modulation, or character from the power beam. The decision unit may beconfigured to determine a characteristic of an object impinging on theguard beam (e.g., speed, direction, size, shape, or composition), andmay also be configured to select a beam-directing element and toinstruct the power beaming unit to direct the power beam toward thebeam-directing element, and further to direct the selectedbeam-directing element to redirect the power beam toward the receivingunit or toward a second beam-directing element. The system may furtherinclude a beam optimization unit configured to use information receivedfrom the receiver to adjust a power beam characteristic (e.g., beam spotsize, shape, power, intensity, or power-time profile). The power beamingunit may be configured to beam power within an enclosed space, and maybe configured to beam power directly to the receiving unit or to abeam-directing element configured to redirect the power to the receivingunit. The power beaming unit may be configured to beam electromagneticpower (e.g., optical or RF), and may be configured to gradually increasean amount of power beamed. It may include a laser that generates a powerbeam, and may be configured to beam pulsed or continuous power.

In another aspect, a method for supplying beamed power includesdirecting a composite power beam toward a receiving unit, the compositepower beam including a main power beam and a guard beam substantiallysurrounding the main power beam, receiving a reflection of at least aportion of the composite power beam from the receiving unit, thereflection including a reflection of at least a portion of the guardbeam, monitoring the received reflection to identify an impingement onthe guard beam, and modulating at least the main power beam. Modulatingthe power beam may include suspending or terminating the power beam. Themethod may further include combining the power beam and the guard beamin a substantially collinear arrangement. The guard beam may besubstantially cylindrical, may include a plurality of beams arrangedaround the power beam, may be configured to scan an area substantiallysurrounding the power beam, or may include a plurality of substantiallyconcentric beams. Producing a guard beam may include reflecting energyfrom a retroreflector array located at the receiving unit or reflectingfringes of the power beam. The guard beam may differ in wavelength,polarity, modulation, or character from the power beam. The method mayfurther include determining a characteristic of an object impinging onthe guard beam (e.g., speed, direction, size, shape, or composition).The guard beam may be electromagnetic oracoustic. The method may furtherinclude using the monitored received reflection to adjust a power beamcharacteristic (e.g., beam spot size, shape, intensity, power, orpower-time profile). The composite power beam may be directed within anenclosed space, and may be beamed directly to the receiving unit or to abeam-directing element configured to redirect the power to the receivingunit. The main power beam may be electromagnetic (e.g., optical or RF),may be of gradually increasing power, and may be continuous or pulsed.

In another aspect, a method for supplying beamed power includesdirecting a composite power beam toward a receiving unit, the compositepower beam including a main power beam and a guard beam substantiallysurrounding the main power beam, receiving a reflection of at least aportion of the composite power beam from the receiving unit, thereflection including a reflection of at least a portion of the guardbeam, monitoring the received reflection to identify an impingement onthe guard beam, and rerouting the composite power beam. The method mayfurther include combining the power beam and the guard beam in asubstantially collinear arrangement. The guard beam may be substantiallycylindrical, may include a plurality of beams arranged around the powerbeam, may be configured to scan an area substantially surrounding thepower beam, or may include a plurality of substantially concentricbeams. Producing a guard beam may include reflecting energy from aretroreflector array located at the receiving unit or reflecting fringesof the power beam. The method may further include determining acharacteristic of an object impinging on the guard beam (e.g., speed,direction, size, shape, or composition). The guard beam may beelectromagnetic or acoustic, and may differ in wavelength, polarity,modulation, or character from the power beam. Rerouting the compositepower beam may include selecting a beam-directing element andinstructing the power beaming unit to direct the power beam toward theselected beam-directing element, and may further include directing thebeam-directing element to redirect the power beam toward the receiver ortoward a second beam-directing element. The method may further includeusing the monitored received reflection to adjust a power beamcharacteristic (e.g., beam spot size, shape, intensity, power, orpower-time profile). The composite power beam may be directed within anenclosed space, and may be beamed directly to the receiving unit or to abeam-directing element configured to redirect the power to the receivingunit. The main power beam may be electromagnetic (e.g., optical or RF),may include a laser, may be of gradually increasing power, and may becontinuous or pulsed.

In another aspect, a receiving unit for receiving a power beam includesan aperture including a power converter configured to convert the powerbeam to another form and a plurality of retroreflectors arranged aboutthe aperture configured to retroreflect at least a portion of the powerbeam. The power converter may be a photoreceptor (e.g., a photovoltaiccell, a photodiode, or a charge-coupled device), or it may be anelectroacoustic transducer.

In another aspect, a system for supplying beamed power includes a powerbeaming unit configured to supply power to a receiving unit in the formof a power beam, a guard beaming unit configured to produce a guard beamconfigured to substantially surround the power beam and differing inmodulation, polarization, or character from the power beam (e.g., anelectromagnetic or acoustic guard beam), and a beam interruption unitconfigured to respond to a direction from the receiving unit to preventa detected imminent impingement on the power beam. The beam interruptionunit may be configured to suspend, terminate, or reroute the power beamto prevent the detected imminent impingement. The system may furtherinclude a beam combiner configured to combine the power beam and theguard beam in a substantially collinear arrangement. The guard beam maybe substantially cylindrical, may include a plurality of beams arrangedaround the power beam, may be configured to scan an area substantiallysurrounding the power beam, or may include a plurality of substantiallyconcentric beams. The beam interruption unit may be configured todetermine a characteristic of an object impinging on the guard beam(e.g., speed, direction, size, shape, or composition). The power beamingunit may be configured to beam power within an enclosed space, and maybe configured to beam power directly to the receiving unit or to abeam-directing element configured to redirect the power to the receivingunit. The power beaming unit may be configured to beam electromagneticpower (e.g., optical or RF), and may be configured to gradually increasean amount of power beamed. It may include a laser that generates a powerbeam, and may be configured to beam pulsed or continuous power.Direction from the receiving unit may be delivered as an electromagneticsignal, or as a cessation of an electromagnetic signal. In anotheraspect, a system for receiving beamed power from a power source, thebeamed power including a guard beam substantially surrounding a powerbeam and differing in modulation, polarization, or character from thepower beam, includes a power receiving unit configured to accept thepower beam, a detection unit configured to recognize an imminentimpingement on the power beam by detecting an impingement on the guardbeam, and a beam interruption signaling unit configured to transmit asignal to the power source indicating interruption of the guard beam.The detection unit may be configured to distinguish an impingement onthe guard beam from an impingement on the power beam by recognizingmodulation or polarization.

In another aspect, a method of supplying beamed power includes directinga composite power beam toward a receiving unit, the composite power beamincluding a main power beam and a guard beam substantially surroundingthe main power beam (e.g., an electromagnetic or acoustic guard beam),the guard beam differing in modulation, polarization, or character fromthe power beam, receiving information from the receiving unit concerningan imminent impingement on the guard beam, and responding to prevent theimminent impingement on the power beam. Responding to prevent animminent impingement on the power beam may include suspending,terminating, or rerouting the power beam. The method may further includecombining the power beam and the guard beam in a substantially collineararrangement to form the composite power beam. The guard beam may besubstantially cylindrical, may include a plurality of beams arrangedaround the power beam, may be configured to scan an area substantiallysurrounding the power beam, or may include a plurality of substantiallyconcentric beams. The method may further include producing a guard beamby reflecting energy from a retroreflector array located at thereceiving unit. The method may include determining a characteristic ofan object impinging on the guard beam (e.g., speed, direction, size,shape, and composition), or using the monitored received reflection toadjust a power beam characteristic (e.g., beam spot size, shape, power,intensity, or power-time profile). Directing a composite power beam mayinclude beaming power within an enclosed space, and may include beamingpower directly to the receiving unit or beaming power to abeam-directing element configured to redirect the power to the receivingunit. The main power beam may be electromagnetic (e.g., optical or RF),may include a laser, may be of gradually increasing power, and may becontinuous or pulsed. Receiving information from the receiving unit mayinclude receiving a signal from the receiving unit or ceasing to receivea signal from the receiving unit. In another aspect, a system forsupplying beamed power includes a location unit, a first beam-directingmechanism configured to change direction of a power beam, and a powerbeaming unit remote from the beam-directing mechanism, configured tobeam power to the receiving unit by sending a power beam in a pathselected to reach the receiving unit via the beam-directing mechanism.The location unit is configured to locate a receiving unit in need ofpower by broadcasting a beam indicative of its ability to supply powerand receiving a request for power from the receiving unit in response tothe broadcast beam. The power beaming unit is further configured tolocate the beam-directing mechanism, and optionally to communicate thelocation of the beam-directing mechanism to the power beaming unit. Thesystem may include a second beam-directing mechanism, and may furtherinclude beam-directing mechanism selection circuitry configured todirect the power beaming unit to direct the beam toward either the firstor the second beam-directing mechanism. The first beam-directingmechanism may be configured to dynamically adjust the direction of thepower beam to follow a moving power receiver. The location unit may becolocated with the power beaming unit or with the first beam-directingmechanism. The power beaming unit may be configured to beam power withinan enclosed space, and may gradually increase an amount of power beamed.It may beam electromagnetic power (e.g., optical or RF), and may includea laser. The power beam may be pulsed or continuous. In another aspect,a method of beaming power includes broadcasting a signal indicating anability to supply power, receiving a request from a receiving unit inresponse to the broadcast signal, and beaming power from a power beamingunit to a beam-directing unit configured to redirect the power to thereceiving unit. Beaming power may include locating the firstbeam-directing unit and optionally communicating the location of thebeam-directing unit to the power beaming unit. The method may furtherinclude dynamically adjusting the direction of the power beam to followa moving receiving unit. Beaming power to a beam-directing unit mayinclude directing power to a plurality of beam-directing units inseries. Power may be beamed within an enclosed space, and may begradually increased. The power beam may be electromagnetic (optical orRF), and may include a laser. It may be pulsed or continuous.

In another aspect, a system for supplying beamed power includes alocation unit configured to locate a receiving unit in need of power byreceiving a request for power from the receiving unit, a firstbeam-directing mechanism configured to change direction of a power beam,and a power beaming unit remote from the beam-directing mechanism,configured to beam power to the receiving unit by sending a power beamin a path selected to reach the receiving unit via the beam-directingmechanism. The power beaming unit may be further configured to locatethe beam-directing mechanism and optionally to communicate the locationof the beam-directing mechanism to the power beaming unit. The systemmay include a second beam-directing mechanism, and may further includebeam-directing mechanism selection circuitry configured to direct thepower beaming unit to direct the beam toward either the first or thesecond beam-directing mechanism. The first beam-directing mechanism maybe configured to dynamically adjust the direction of the power beam tofollow a moving power receiver. The location unit may be colocated withthe power beaming unit, or with the first beam-directing mechanism. Thepower beaming unit may be configured to beam power within an enclosedspace, and to gradually increase power. The power beam may beelectromagnetic (optical or RF), and may include a laser. It may bepulsed or continuous.

In another aspect, a system for providing beamed power to a mobilereceiving unit includes a first power beaming unit configured to beampower to a receiving unit in a first power zone and a second powerbeaming unit configured to beam power to the receiving unit in a secondpower zone. The first power beaming unit is configured to terminatepower beaming as the receiving unit moves out of the first power zoneand the second power beaming unit is configured to initiate powerbeaming as the receiving unit moves into the second power zone. Thefirst power beaming unit may be configured to detect that the receivingunit has moved into the second power zone and to communicate to thesecond power beaming unit that the receiving unit has moved into thesecond power zone. The first power beaming unit may be configured tobeam power within an enclosed space, and to gradually increase power. Itmay beam power directly to the receiving unit, or to a beam-directingelement configured to redirect the power to the receiving unit. Thepower beam may be electromagnetic (optical or RF), and may include alaser. It may be pulsed or continuous.

In another aspect, a method for providing beamed power to a mobilereceiving unit includes beaming power from a first sending location tothe receiving unit at a first receiving location, determining that thereceiving unit is moving from the first receiving location to a secondreceiving location, and beaming power from a second sending location tothe receiving unit at the second receiving location. Determining mayinclude detecting from the first sending location that the receivingunit is moving away from the first receiving location and communicatingto the second sending location that the receiving unit is moving towardthe second receiving location, or it may include receiving informationfrom the receiving unit. Power may be beamed within an enclosed space,and may be gradually increased. The method may include beaming powerdirectly to the receiving unit, or to a beam-directing elementconfigured to redirect the power to the receiving unit. The power beammay be electromagnetic (optical or RF), and may include a laser. It maybe pulsed or continuous.

In another aspect, a power source configured to beam power to areceiving unit includes a location unit, a first power beaming unitconfigured to beam power to the receiving unit, and a decision unitconfigured to determine that the receiving unit should be powered by asecond power beaming unit and to direct the first power beaming unit todiscontinue beaming power to the receiving unit upon transfer ofresponsibility for power beaming to the second power beaming unit. Thelocation unit is configured to locate a receiving unit in need of powerby initiating contact with the receiving unit by broadcasting a signalindicative of its ability to supply power, and receiving a request forpower from the receiving unit in response to the broadcast signal. Thedecision unit may be configured to determine that the receiving unitshould be powered by a second power beaming unit by determining that thereceiving unit has entered a power zone corresponding to the secondpower beaming unit. The first power beaming unit may be configured tobeam power within an enclosed space, and to gradually increase power. Itmay beam power directly to the receiving unit, or to a beam-directingelement configured to redirect the power to the receiving unit. Thepower beam may be electromagnetic (optical or RF), and may include alaser. It may be pulsed or continuous. In another aspect, a system forproviding beamed power to a mobile receiving unit includes a powerbeaming unit configured to beam power (e.g., electromagnetic power suchas optical or RF) to the mobile receiving unit, and a path predictionunit configured to predict a motion of the mobile receiving unit. Thepower beaming unit may be configured to beam power directly to thereceiving unit or to a beam-directing element configured to redirect thepower to the receiving unit, and it may include a laser that generates apower beam. The path prediction unit may be configured to detect or toreceive a signal from the receiving unit indicating a speed or directionof movement. It may use a history of movement of the receiving unit topredict a path for the unit.

In another aspect, a system for providing beamed power to a mobilereceiving unit includes a power beaming unit configured to beam powerand a plurality of beam-directing components configured to dynamicallyredirect power from the power beaming unit to the mobile receiving unit.The system may further include a movement determination unit configuredto determine a movement characteristic of the mobile receiving unit,which may be configured to select a beam-directing component arranged toredirect power to the mobile receiving unit. The movement determinationunit may be further configured to transmit an instruction to theselected beam-directing component indicating a beam direction.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic of power beaming system.

FIG. 2 is a flow chart illustrating operation of a power source.

FIG. 3 is a flow chart illustrating operation of a power receiver.

FIG. 4 is a schematic of a power source.

FIG. 5 is a schematic of a power beaming system including multiple powerbeaming units.

FIG. 6 is a flow chart illustrating operation of a power sourceincluding multiple power beaming units.

FIG. 7 is a flow chart illustrating operation of a power source servingmultiple power receiving units.

FIG. 8 is a schematic of a power beaming system including a guardbeaming unit with a monitor at the power beaming side.

FIG. 9 is a flow chart illustrating operation of a power beaming systemincluding a guard beam monitor at the power beaming side.

FIG. 10 is a schematic of a power beaming system including a guardbeaming unit with a monitor at the power receiver side.

FIG. 11 is a flow chart illustrating operation of a power beaming systemincluding a guard beam monitor at the power receiver side.

FIG. 12 is a schematic of a power beaming system configured to usebeam-directing mechanisms to direct a power beam to a receiver.

FIG. 13 is a schematic of a power beaming system configured to hand offpower beaming from one unit to another as a receiver moves between powerzones.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here.

As used herein, “broadcasting” encompasses transmitting a signalsimultaneously to a plurality of locations, for example by transmittinga signal into space in a pattern that encompasses a substantial solidangle. In contrast, “scanning” encompasses sequentially transmitting asignal to a plurality of locations, for example by moving a narrow-beamtransmitter to sweep through an area of space.

As used herein, “aperture” encompasses any region of a power receiverthat converts beamed power to useful energy, such as a photoconverterregion, or an opening or optic element that directs light to aphotoconverter.

FIG. 1 illustrates a power beaming system for sending beamed power to areceiving unit. As shown, the system includes a power source 10including a power beaming unit 12 and a location unit 14. Power beamingunit 12 may be configured to beam power in any of a variety of forms,for example as a laser or other electromagnetic beam (such as a visiblelight, microwave, radio frequency, ultraviolet, or infrared beam), as aparticle beam, or as an acoustic beam (such as an ultrasonic beam).Power transmission may be continuous, pulsed, or according to a morecomplex spatio-temporal profile. Location unit 14 includes a transmitter16 configured for a wide-area broadcast and a receiver 18 configured toreceive a signal from a receiving unit in need of power. Furtherillustrated is a power receiver 20, which includes a signal receiver 22,a transmission unit 24, and a power receiving unit 26. The illustratedembodiment is configured to beam power within an enclosed space (e.g., aroom), while other embodiments may be configured for power beamingoutdoors or in open spaces.

In some embodiments, transmitter 16 may be configured to initiatebroadcasting on a time schedule (e.g., every 20 milliseconds, every fiveminutes, every hour during the workday, or during a designated poweravailability period), or in response to a detected condition. Forexample, transmitter 16 may initiate broadcasting when it senses (orreceives information from another source) that a person has entered theroom (e.g., by sensing motion or sound, or by receiving an indicationthat the room lights have turned on), or it may detect a passive markerindicating a compatible power receiver (e.g., an identifying distinctivemark such as a checkerboard pattern or a distinctively coloredretroreflector that may be detected by a visual scan). Such markers mayfurther convey information about an associated receiver 20, such aspower requirements, identity, or location of reception “target” (e.g.,indicating that an antenna is placed between two such markers).Transmitter 16 may be configured to broadcast an electromagnetic signal(e.g., an optical or RF signal) or an acoustic signal, and receiver 18may be configured to receive an electromagnetic or acoustic signal,which may not be of the same character or frequency as the signalbroadcast by transmitter 16.

In some embodiments, power source 10 may further include a decision unit(not shown), which is configured to determine whether to beam power inresponse to a request from a power receiver 20. This decision may bebased at least in part upon information received from the power receiver20, such as a requested power characteristic or proposed payment terms.Determining whether to beam power may include deciding whether toinitiate power beaming in response to a request (for example, decidingwhether proposed payment terms are adequate or whether the power sourceis able to supply power meeting the requested parameters), decidingwhether to suspend power beaming during operation (for example, to beampower to a higher-priority unit or to one that needs power only for alimited time), or deciding whether to terminate power beaming (forexample, because a higher-priority request or one offering more generouspayment terms is received, or because the power receiver indicates thatpower is no longer required). In embodiments where the power source 10supplies power to a plurality of power receivers 20 on a sequentialbasis, the decision unit may also control scheduling of powertransmission sequentially to the plurality of power receivers. Thedecision unit may further be configured to receive a transmission fromthe receiving unit confirming receipt of power or amount of powerreceived, and in the latter case, may compare the amount of powerreceived with the amount transmitted, for example to determineefficiency.

In some embodiments, location unit 14 may be configured to transmit datato power receiver 20, either via transmitter 16 or via a separatechannel such as a separate transmitter or a wired connection (notshown), or via modulation of power beamed from power beaming unit 12.This data transmission may allow location unit 14 to negotiate powerdelivery terms (e.g., how much power on what schedule) or payment terms(e.g., price per unit of power or form of payment) with power receiver20, or to authenticate the identity of power receiver 20 and monitorreceipt of power by the unit.

In some embodiments, power may be beamed directly from power source 10to power receiver 20, as indicated by dotted line 30 in FIG. 1.Additionally or alternatively, the power beam may be redirected bybeam-directing elements, as indicated by dotted line 32 in FIG. 1,illustrating a power beam bouncing off of reflector 34. While theillustrated embodiment includes a reflector, it will be understood thatother beam-directing elements may also be used, including but notlimited to electromagnetic fields, waveguides, beam splitters, oroptical fibers. Beam-directing elements may be used, for example, toavoid physical obstacles, to provide an adjustable beam direction from afixed power source 10, or to split or modulate the power beam.

In some embodiments, power source 10 may include an impingement detector(not shown) configured to detect that the power beam has encountered anobstruction. The power beaming unit 12 may be configured to suspend orterminate power if an obstruction is detected. In some embodiments, theimpingement detector may detect impingement by detecting scattered orreflected radiation, either from the main beam or from a guard beam akinto that described in U.S. Pat. No. 6,633,026, incorporated herein byreference, which describes a high-intensity power beam surrounded by alow-intensity “curtain,” in which the high-intensity power beam isinterrupted if the power receiver detects a break in the low-intensity“curtain” indicating impingement.

Power source 10 may be capable of delivering power at a range ofintensities. In some embodiments, the power beam may initially be at alow intensity and gradually be increased, for example to allow time todetect impingement of the power beam at low power to minimize anypotential damage, or to allow optimization of the power beam path,convergence, or shape (e.g., using beam-directing elements as describedabove, including possibly inserting astigmatism into the beam to matchreceiver shape or attitude) at low power to maximize efficiency of powertransfer.

In the illustrated embodiment, transmission unit 24 is configured totransmit a request for power. For example, transmission unit 24 may beconfigured to transmit the request by generating and transmitting arequest signal, or by reflecting the broadcast signal (e.g., byretroreflecting and modulating the broadcast signal). The request forpower may include identity or location information for power receiver20, information about power needs of power receiver 20, or informationabout economic parameters of requested power transmission. Signalreceiver 22 may be configured to receive an electromagnetic (e.g., RF oroptical) signal or an acoustic signal. Power receiving unit 26 isconfigured to accept power beamed from a power unit (e.g., to use topower a device), and may also accept data transmission from the powerunit, for example as a carrier wave on the power beam or via a separatechannel. This data transmission may include, for example, negotiation ofpower delivery characteristics or payment characteristics, negotiationof termination of power delivery, identity authentication information,or power receipt monitoring information. Power receiving unit 26 may beconfigured to reposition itself to adjust power reception (for example,changing attitude to align with a power beam direction), and maycommunicate with a user, for example to report a power reception levelor to recommend a change in orientation or position to adjust powerreception.

FIG. 2 is a flow chart illustrating operation of a power source such aspower source 10 of FIG. 1. As shown in step 40, location unit 14broadcasts a signal via transmitter 16 to a wide area surrounding powersource 10. As shown in step 42, location unit 14 receives a signal frompower receiver 20 via receiver 18. In some embodiments, this signal mayinclude location information for power receiver 20, either explicitly(e.g., in the form of an encoded signal, for example a modulatedreflected signal or an independent signal) or implicitly (e.g., thelocation may be determinable from the direction of the received signal,which may be determined, for example, by scanning using a directionalantenna or by imaging). Optionally, location unit 14 may interpret thissignal or other information to determine a receiver location, as shownin step 44. In some embodiments, the signal may include identifyinginformation for power receiver 20, in which case, location unit 14 mayuse the identifying information to determine a location for powerreceiver 20 (e.g., by accessing a location database, or by determining aprevious location for the same unit). In some embodiments, location unit14 may determine an attitude of the receiving unit (e.g., by signalstrength, by interpreting a signal including attitude information, or byimaging).

As shown in step 46, power source 10 beams power to power receiver 20via power beaming unit 12.

FIG. 3 is a flow chart illustrating operation of a power receiver suchas power receiver 20 of FIG. 1. As shown in step 50, power receiver 20receives a broadcast signal indicating availability of power (e.g., frompower source 10) via signal receiver 22. As shown in step 52, powerreceiver 20 then transmits a request for power via transmission unit 24.In some embodiments, transmission unit 24 may include a transmitter thatgenerates and transmits a request signal, as shown in step 54.Additionally or alternatively, transmission unit 24 may include aretroreflector or similar apparatus that reflects the broadcast signalback to power source 10 to indicate the presence of power receiver 20,as shown in step 56. In some embodiments, this “reflection” may beaccomplished by passive reflection, or it may encompass modulation orpowered retransmission of the original signal (e.g., by use of atransponder). The request signal may include location information forpower receiver 20, either explicitly (e.g., in the form of an encodedsignal) or implicitly (e.g., the location may be determinable from thedirection of the received signal, for example because power receivingunit 26 is known to be coterminous with transmission unit 24 or to havea known offset therefrom).

The request signal may include information describing power needs ofpower receiver 20, such as beamed power parameters (e.g., power type,wavelength, pulse characteristics, power amount, energy amount,polarization, power-vs.-time profile, time window, offset of aperturesite from receiving unit signal location, aperture size of receivingunit, or attitude of aperture of receiving unit) or economic parameters(e.g., acceptable price, ability to pay, mode of payment, or identifyinginformation for the receiving unit). These parameters may be explicitlytransmitted, or they may be determinable by location unit 14 on thebasis of identifying information for the power receiver 20.

As shown in step 58, power receiver 20 receives beamed power in responseto the request via power receiving unit 26.

FIG. 4 illustrates a power source configured to scan a signaladvertising power availability. The illustrated embodiment includes alocation unit 70, including a transmitter 72 configured to scan anarrow-beam signal (e.g., a focused signal) through a space (e.g., anenclosed space such as a room), and a receiver 74 configured to receivea request for power in the form of a reflection of the signal, and apower beaming unit 76 configured to beam power in response to therequest. Transmitter 72 may be configured to transmit an electromagneticsignal (e.g., an optical or RF signal) or an acoustic signal, and may beconfigured to move the beam source to scan the area (as shown in FIG.4), or may include an adjustable beam-directing element such as a mirrorto scan the beam. The unit may scan continuously, on a time schedule, orin response to a detected condition. For example, the unit may detect(or receive information detected by another device) indicating that aperson has entered the room, and may then initiate a scan for devicesthat may be in need of power (e.g., devices carried by the enteringperson).

In some embodiments, the received reflected signal may be modulated, andlocation unit 70 may be configured to interpret the modulation, forexample in order to receive data about the reflecting power receiversuch as its location, attitude, or identifying information. Locationunit 70 may also be configured to determine location, attitude, or otherattributes using the signal path from the receiving unit, or by usingidentifying information provided by the receiving unit, for example todetermine a previous location for the same unit or to access a databaseof known receiving unit locations. The received reflected signal may bemodulated by the receiving unit or by another element in the signalingpath such as a beam-directing element. The receiving unit may alsocommunicate with the power beaming unit via another channel, such as anelectromagnetic or acoustic transmission, a wired channel, or via theinternet, in addition to reflecting the received signal.

The power unit of FIG. 4 may further include a decision unit (notshown), which may be configured to determine whether or how to beampower from the power unit in response to a request, as described hereinin connection with FIG. 1.

In some embodiments, location unit 70 may be configured to transmit datato the receiving unit, for example via transmitter 72, by modulating thebeam power of power beaming unit 76, or via a separate channel (notshown) such as another transmitter or another communications channelsuch as an internet connection. For example, location unit 20 may beconfigured to negotiate power delivery or payment characteristics, toauthenticate identity of the receiving unit, or to monitor receipt ofpower by the receiving unit.

FIG. 5 is a schematic illustrating a system for supplying beamed powerto a receiving unit including a location unit 90 and a plurality ofpower beaming units 92, 94. While the illustrated embodiment includestwo power beaming units, more may be included according to powerrequirements, space limitations, and other design constraints. Powerbeaming units 92, 94 need not be identical. Location unit 90 includes abroadcast transmitter 96 and a receiver 98. As shown, location unit 90is offset from power beaming units 92, 94, but location unit 90 may alsobe colocated with one or more of the plurality of power beaming units.In some embodiments, there may further be additional location units (notshown). The illustrated system further includes an optional decisionunit 100 which is connected to power beaming units 92, 94. Decision unit100 is configured to accept location information from location unit(s)90 and to designate one or more of power beaming units 92, 94 to beampower to a receiving unit in response to a request. The system may beconfigured to beam power either to a single requesting power receiver(from one or multiple sources) or to a plurality of receivers.

Decision unit 100 may use any of a variety of inputs to determine whichpower beaming unit(s) will supply power to a given receiver, includingphysical proximity, unobstructed power beam length, requested powercharacteristics (e.g., type, wavelength, pulse characteristics,quantity, polarization, power-vs-time profile, or time window),transaction characteristics (e.g., acceptable price, ability to pay,mode of payment, or identifying information for a receiving unit), orhistorical information (e.g., historical frequency of interruption of agiven beam path). For example, decision unit 100 may determine that onepower beaming unit is better suited to supply power at a requestedfrequency, and may direct that power beaming unit to beam power to therequesting receiving unit. In some embodiments, it may determine whichpower beaming unit has the shortest optical path length to the receivingunit (taking into account any beam-directing elements such as mirrorsthat may be interposed between the power beaming unit and the receiver),and may select the power beaming unit having the shorted unobstructedbeam path to the receiver (which may or may not be the power beamingunit in closest physical proximity to the receiver), or it may selectthe power beaming unit having the highest projected power intensity forthe receiver location, taking into account angle of arrival of the powerbeam. In some embodiments, decision unit 100 may use a multipointoptimization algorithm, for example one designed to ensure best overallpower delivery according to a selected figure-of-merit even if no singlereceiver receives power from the “best” source or vice versa. Decisionunit 100 may further include circuitry for determining whether toinitiate, suspend, or terminate power beaming for any or all powerbeaming units, for example in response to changing geometrical oreconomic conditions.

Receiver 98 may be configured to receive a request for power in the formof a transmission from a receiving unit or in the form of a reflectionof the broadcast signal from the receiving unit, which may be amodulated reflection, as described elsewhere herein. The request forpower may include location information for the receiving unit, eitherexplicitly in a received signal or implicitly (e.g., by inference from abeam path or by identification of the requesting receiving unit). Thesystem may include a plurality of receivers 98 or of broadcasttransmitters 96, for example to provide uniform coverage throughout anenclosed space containing obstacles.

Power beaming units 92, 94 may be configured to beam power to aplurality of power receivers. In some embodiments, each power beamingunit may beam power to a single receiver, while in other embodiments,one power beaming unit may serve multiple receivers, or multiple powerbeaming units may serve a single receiver. For example, a power beamingunit may be configured to split an output beam (e.g., via a beamsplitter or spatial divider) and to direct each portion of the splitbeam to a different power receiver, or the power beaming unit may beconfigured to beam power to different power receivers serially, forexample by scanning a beam to each power receiver in turn. The systemmay determine (e.g., using decision unit 100) relative priority ofdifferent power receivers for power to determine how to split or scan abeam from a power receiver.

In some embodiments, power beaming units 92, 94 may share a commonenergy source. For example, a single laser or other electromagnetic beamsource (not shown) may illuminate a plurality of optical fibers or otherenergy conduits that “pipe” energy to power beaming units 92, 94 fortransmission from physically separated points.

FIG. 6 is a flow chart illustrating operation of a system includingmultiple power beaming units such as the system illustrated in FIG. 5.As shown in step 120, broadcast transmitter 96 broadcasts a signalindicating power availability. In some embodiments, this broadcast maybe in response to a triggering unit (not shown), which may signalbroadcast transmitter 96 to broadcast in response to a condition such asa person entering the room, or in response to receipt of a signal suchas an internet transmission or a request from the receiving unit. Inresponse to the broadcast, receiver 98 receives a request for power froma receiving unit as shown in step 122. As discussed above, this requestmay be in the form of a direct transmission, or it may be a reflection(optionally modulated) of the broadcast signal. As shown in step 124,the system selects one or more power beaming units 92, 94 to respond tothe request (e.g., by operation of a decision unit 100), and beams powerfrom the selected unit(s) as shown in step 126. In some embodiments,receiver 98 may identify preferred power beaming unit(s) and communicatea request for power from one or more specific units.

FIG. 7 is a flow chart illustrating operation of a system supplyingbeamed power to multiple receiving units. The system may include asingle power beaming unit as shown in FIG. 1, or multiple power beamingunits as shown in FIG. 5. As shown in step 130, the system broadcasts asignal indicating power availability. The system receives a first powerrequest and a second power request in response to the broadcast, asshown in steps 132 and 134 respectively. The system then determines(e.g., by operation of a decision unit) relative priority of the powerrequests, as shown in step 136. For example, the system may select thepower request which generates maximum revenue or profit, or it mayselect the power request that may be most efficiently served by thesystem, or it may select a power request by any other suitablecriterion. The selection criterion may include reference to datasupplied by one or both requesting receiving units, such as power type,wavelength, pulse characteristics, power amount, polarization,power-vs-time profile, time window, acceptable price, ability to pay,mode of payment, or identifying information for the receiving unit(s).As shown in steps 138 and 140, the system then selects a power beamingunit to beam power to the higher priority requester (if the systemincludes multiple power beaming units), and further may select a powerbeaming unit to beam power to the lower priority requester. These powerbeams may originate from the same or separate power beaming units, andin some embodiments, more than one power beaming unit may supply powerto the same receiver. As shown in step 142, the system beams power fromthe selected power beaming units to the requesting receiving unit(s).

FIG. 8 is a schematic of a power beaming system that delivers a powerbeam substantially surrounded by a guard beam. Power beaming unit 160 isconfigured to supply power in the form of power beam 162 (e.g., a laserbeam), and guard beaming unit 164 is configured to produce a guard beam166. In the illustrated embodiment, these beams are combined in beamcombiner 168 to be substantially collinear. The broader guard beam 166thus surrounds (and optionally overlaps) the narrower power beam 162.Beam combiner 168 may be omitted if power beaming unit 160 and guardbeaming unit 164 are configured to produce the desired beam geometry.For example, guard beaming unit 164 may include multiple guard beamgenerators arranged around power beaming unit 160 to produce overlappingor non-overlapping guard beams 166 that collectively surround power beam162.

The combined beam is directed to power receiver 170, where at least aportion of the beam is reflected back to guard beam receiver 172. Insome embodiments, power receiver 170 may be configured to absorb asubstantially greater fraction of power from power beam 162 than fromguard beam 166, reflecting a substantially greater fraction of powerfrom guard beam 166 (for example, guard beam 166 may be at a nonabsorbedfrequency for receiver 170 as compared to power beam 162). For clarityin the illustrated embodiment, the reflected path is somewhat angledfrom the beam path, but the reflection may also be close to the originalbeam path, for example by use of a retroreflector at the power receiver170, or may be at any selected angle calculated to reach guard beamreceiver 172.

Power beam 162 will typically (but not necessarily) have a higher powerdensity than guard beam 166. In addition, the beams may (but need not)differ in wavelength, polarity, modulation, or character (e.g., anelectromagnetic power beam and an acoustic guard beam). If the beamsdiffer in any of these characteristics, the differing characteristic(s)may be used to differentiate impingement on guard beam 166 fromimpingement on power beam 162 as further discussed in connection withFIG. 10 and FIG. 11. In addition, guard beam 166 need not behomogeneous, and the location of the impingement may be inferred fromthe characteristics of the reflected signal. For example, guard beam 166may comprise a plurality of beams of different frequency arranged aroundpower beam 162. By monitoring which frequency or frequencies areinterrupted, one or more characteristics of the impinging object may beinferred, such as speed, direction, size, shape, or composition. Thisinformation may be used, for example, to predict when the object willleave the beam path and allow resumption of power beam 162. Similarly,guard beam 166 may be a relatively narrow beam rapidly scanned aroundpower beam 162 (or a series of narrow guard beams surrounding power beam162 which are illuminated in series), rather than a wide beamcontinuously surrounding power beam 162 as illustrated in FIG. 8. Insuch embodiments, characteristic(s) of the impinging object may bedetermined by monitoring the temporal profile of guard beam intensity.Guard beam 166 may also include a plurality of substantially concentricguard beams. In some such embodiments, impingement on an outer guardbeam may warn power beaming unit 160 to prepare to suspend transmission,and transmission may be suspended or terminated if an inner guard beamis also impinged.

Guard beam receiver 172 monitors the reflected guard beam 166. If theamount of energy received from guard beam 166 changes character in a wayindicating a possible impingement on the beam (e.g., beam power drops),decision circuitry 174 may direct power beaming unit 160 to suspend orterminate transmission of power beam 162. Because guard beam 166substantially surrounds power beam 162, power can be cut off in responseto impingement of the guard beam before an object or person intersectsthe power beam and possibly suffers damage. Alternatively, instead ofsuspending transmission of power beam 162, the system may reroute thepower beam to avoid the impinging object. For example, in theillustrated embodiment, beam combiner 168 may direct the combined beamto a beam-directing element 176 (in the embodiment illustrated, amirror), which redirects the combined beam toward power receiver 170. Insome embodiments, there may be a plurality of guard beam receivers (notshown). Additionally or alternatively, reflected guard beam 166 may alsobe used to monitor quality of power transmission. For example, if guardbeam 166 is being reflected on only one side, it may indicate that powerbeam 162 is not targeted directly at power receiver 170, or that theshape of the beam spot should be adjusted to match the apparent shape ofpower receiver 170 (which may change depending on receiver attitude).

In some embodiments, the cylindrical geometry of reflected guard beam166 may be generated by a retroreflector. For example, a noncollimatedlight source at power beaming unit 160 may be reflected back to the unitby a retroreflector array (e.g., 3M Scotchlite™). A retroreflector arraysurrounding a main power receiver target may also reflect back fringesof power beam 162 to act as reflected guard beam 166. In someembodiments, a retroreflector at the power receiver may have adistinguishable spatial structure that allows inference ofcharacteristics or geometry of an impinging object.

FIG. 9 is a flow chart illustrating a method of supplying beamed power,for example using a system such as that shown in FIG. 8. As shown instep 190, the method includes directing a composite beam toward areceiving unit, where the composite beam includes a power beam 162 and aguard beam 166 substantially surrounding the power beam. As shown instep 192, a reflection of the composite beam is received from thereceiving unit, the reflection including at least a portion of the guardbeam 166. The method includes monitoring the received reflection toidentify an impingement on the guard beam 166, as shown in step 194.Finally, the method may include either suspending at least the powerbeam 162 as shown in step 196, or rerouting the composite beam as shownin step 198. In some embodiments, upon starting or rerouting thecomposite beam, the system may first transmit only a guard beam whilechecking to confirm that an unobstructed beam path is available forpower transmission.

FIG. 10 is a schematic of another power beaming system including a powerbeaming unit 160, a guard beaming unit 164, and a beam combiner 168. Theguard beam 166 differs from the power beam 162 in modulation orpolarization. After exiting beam combiner 168, guard beam 166 and powerbeam 162 are received at power receiver 210, which is configured todifferentiate between guard beam 166 and power beam 162 by trackingtheir differing characteristics such as modulation or polarization. Inthe illustrated embodiment, sensors 212 are arranged to monitor guardbeam 166, while the main body of receiver 210 converts power beam 162into electrical energy to power a device (e.g., a laptop computer), butseparate sensors may not be required in all embodiments. If powerreceiver 210 detects that guard beam 166 has been at least partiallyinterrupted by an impinging object which may intersect power beam 162,it directs transmitter 214 to communicate with beam interruption unit216. Upon receipt of a communication (including a possible cessation ofcommunication as discussed hereinafter) from transmitter 214 indicatingimpingement, beam interruption unit 216 directs power beaming unit 160to suspend or reroute the beam. In some embodiments, a “fail safe”configuration for transmitter 214 may be used, in which transmittercontinuously transmits to beam interruption unit 216 until animpingement occurs. If beam interruption unit 216 fails to detect asignal from transmitter 214, it directs power beaming unit 160 tosuspend, reroute, or terminate power beam 162. As discussed inconnection with FIG. 8, if guard beam 166 is not homogenous, receiver210 may also infer a location or direction of motion of the impingingobject, and this information may be conveyed to beam interruption unit216.

FIG. 11 is a flow chart illustrating a method of preventing impingementon a power beam. As shown in step 220, the method includes receivingbeamed power from a power source. The beamed power includes a guard beamsubstantially surrounding a power beam and differing therefrom inmodulation or polarization. As shown in step 222, the method includesdetermining that an object has impinged upon the guard beam, and asshown in step 224, transmitting a signal to the power source to indicateimpingement on the guard beam. Impingement on the guard beam may bedetermined by recognizing the modulation or polarization of the guardbeam that differs from that of the power beam. In some embodiments,determining that an object has impinged may include determininginformation about the impinging object (e.g., location, speed, oroptical properties), and transmitting a signal may include transmittingthe determined information.

FIG. 12 is a schematic illustrating a power beaming system configured toaccess one or more beam-directing mechanisms (e.g., relays). The systemincludes a location unit 240 including a transmitter 242 configured tobroadcast a beam indicative of the system's ability to supply power anda receiver 244 configured to receive a request for power from areceiving unit. The system further includes at least one beam-directingmechanism 246 configured to change direction of a power beam. In theillustrated embodiment, the beam-directing mechanism 246 is a turningmirror, but beam-directing mechanisms need not be mobile. In someembodiments, a combination of fixed and turning mirrors may be used, orfine beam adjustments may be geometrically magnified by the use ofcurved mirrors or analogous systems. The illustrated embodiment furtherincludes optional additional turning mirrors 248 and 250. The systemfurther includes a power beaming unit 252 remote from the beam-directingmechanism(s) that is configured to beam power to a receiving unit viathe beam-directing mechanism(s). In embodiments including multiplebeam-directing mechanism, the beam may be directed by one or'more of thebeam-directing mechanisms. In the illustrated embodiment, location unit240 is colocated with power beaming unit 252, but it may also becolocated with a beam-directing mechanism or freestanding.

In some embodiments, the power beaming unit may be configured todynamically locate the beam-directing mechanism(s), for example byscanning a low-power search beam to search for reflections or bybroadcasting a signal requesting acknowledgement from beam-directingmechanisms configured to work with the power beaming unit.Alternatively, the location unit may be configured to locatebeam-directing mechanism(s) and to communicate their locations to thepower beaming unit.

In embodiments in which the beam-directing mechanism is adjustable(e.g., the turning mirrors illustrated in FIG. 12), the beam-directingmechanism may be configured to dynamically adjust the direction of thepower beam to follow a moving power receiver as it moves. Thebeam-directing mechanism may be configured to monitor the position ofthe power receiver (e.g., optically), or to receive information aboutthe location of the power receiver from the power receiver (e.g., via awireless connection).

FIG. 13 is a schematic of a system including multiple power zones. Firstpower beaming unit 270 is configured to beam power to a receiver infirst power zone 272, and second power beaming unit 274 is configured tobeam power to a receiver in second power zone 276. The system isconfigured to determine the position of power receiver 278 within theroom, so that first power beaming unit 270 beams power to it while it isin first power zone 272. As it moves from first power zone 272 to secondpower zone 276, first power beaming unit 270 discontinues powertransmission and second power beaming unit 274 initiates powertransmission. The system may further include a decision unit 280configured to determine the location of power receiver 278 and to directpower beaming units 270, 274 to initiate or terminate power beaming asreceiver 278 moves to and from their respective power zones.

Determining the location of power receiver 278 may simply includedetermining which zone holds the power receiver, or it may includedetermining the power receiver's position within the zone. Position maybe determined by a variety of methods, including scanning, imaging,communication with the power receiver, or monitoring of traffic acrosspower zone borders.

Various embodiments of power beaming units, receivers, and associatedmethods have been described herein. In general, features that have beendescribed in connection with one particular embodiment may be used inother embodiments, unless context dictates otherwise. For example, theguard beam systems described in connection with FIG. 8 may be employedin any of the embodiments described herein. For the sake of brevity,descriptions of such features have not been repeated, but will beunderstood to be included in the different aspects and embodimentsdescribed herein.

It will be understood that, in general, terms used herein, andespecially in the appended claims, are generally intended as “open”terms (e.g., the term “including” should be interpreted as “includingbut not limited to,” the term “having” should be interpreted as “havingat least,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage ofintroductory phrases such as “at least one” or “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a receiver” should typically be interpreted to mean “atleast one receiver”); the same holds true for the use of definitearticles used to introduce claim recitations. In addition, even if aspecific number of an introduced claim recitation is explicitly recited,it will be recognized that such recitation should typically beinterpreted to mean at least the recited number (e.g., the barerecitation of “two power beaming units,” or “a plurality of powerbeaming units,” without other modifiers, typically means at least twopower beaming units). Furthermore, in those instances where a phrasesuch as “at least one of A, B, and C,” “at least one of A, B, or C,” or“an [item] selected from the group consisting of A, B, and C,” is used,in general such a construction is intended to be disjunctive (e.g., anyof these phrases would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, or A, B, and C together, and may further include more than oneof A, B, or C, such as A₁, A₂, and C together, A, B₁, B₂, C₁, and C₂together, or B₁ and B₂ together). It will be further understood thatvirtually any disjunctive word or phrase presenting two or morealternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” will be understood to include the possibilities of “A”or “B” or “A and B.”

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

1.-141. (canceled)
 142. A method of requesting power from one of aplurality of power beaming units, the method comprising: receiving abroadcast signal including location information for a plurality of powerbeaming units; selecting a subset of the plurality of power beamingunits for a power request; and transmitting a request signal requestingpower transmission from the subset.
 143. The method of claim 142,wherein receiving a broadcast signal includes receiving a plurality ofbroadcast signals.
 144. The method of claim 142, wherein receiving abroadcast signal includes receiving a broadcast signal from each memberof the plurality of power beaming units.
 145. The method of claim 142,wherein receiving a broadcast signal includes receiving a single signaldescribing all members of the plurality of power beaming units.
 146. Themethod of claim 142, wherein receiving a broadcast signal includesreceiving information about power transmission characteristics of atleast one of the power beaming units.
 147. The method of claim 142,wherein selecting a subset includes determining which members of theplurality of power beaming units are compatible with a power receiver.148. The method of claim 142, further comprising receiving a powertransmission from at least one member of the subset.